I'm going to piggyback on what Jana is saying with this:
The world ISN'T "full of such monsters." The truth is that we are now a voracious human culture which is partly built around and supported by a 24-hour news cycle. These events can be broadcast in several different media and pointed out, where they might have simply gone under the radar or been local news before.
As such, we as a culture are being exposed to more and more of these stories, and for those people who already have enough trouble reconciling reality with what they see on television, it just makes things worse. When I took my broadcasting courses in college, I heard it referred to as "Scary World Syndrome," and the people who are most likely to succumb to it are the ones who weren't raised in a time of extensive mass media coverage of such things.
Jana is absolutely correct in that there are far more "helpers" than perpetrators. It's just that news outlets feel like the perps get more ratings than the "feel good" "helper" stories. Which are people more likely to watch: the horrific aftermath of an execution-like mass murder spree, or people spooning up soup at the local homeless shelter?
The public encourages such spectacles to be public knowledge by their 'vote,' which in this case is readership/listenership/viewership. As long as the masses are entertained by violence, there will always be a media waiting in the wings to cover it.
That said, this article doesn't even begin to undertake the REAL problem: why? We know that it happened, but we may never have a suitable solution to "why?" Why pistol-whip the kid? I understand the cash grab, but what purpose did the baby serve? We will probably never understand to a satisfactory level, and it won't be news-worthy when we do, because we will have moved on to the next person who did something even more ludicrous.